Comparison and evaluation of the current staging of cutaneous carcinomas

Background: Recently the "Union for International Cancer Control" (UICC) and the "American Joint Committee on Cancer" (AJCC) changed their TNM (tumor, node, metastasis) classification of cutaneous carcinomas.

Methods: We compared these classifications, tested their practicability with 615 prospectively collected, unselected, primary cutaneous squamous cell carcinomas, and introduced additional classification criteria.

Results: Neither classification contains information about prognosis. Non-metastasizing types of cutaneous carcinoma should be excluded. The vermilion border of the lower lip and the eyelids should be included. Both systems have been improved, but in part they are irreproducible. The AJCC has introduced six "high-risk features" to differentiate between T1 and T2. However, this does not seem reasonable. Only rare cases are classified as T4. Both systems have different N classifications. A clinical cT classification based on tumor size 2 cm seems reasonable but not sufficient. It should be complemented by a postoperative p (pathologic) T classification based on tumor thickness: "no risk"≤ 2 mm thickness (0% risk of metastasis), "low risk" > 2 mm to 6 mm thickness (4% risk of metastasis), and "high risk" > 6 mm thickness (16% risk of metastasis). Immune suppression, poor differentiation/desmoplasia, and the ear as tumor site are additional risk factors for metastasis, currently not evaluable.

Conclusions: The classifications are unsuitable for a realistic estimate of the risk of metastasis which is possible using a combination of tumor size and thickness. The N staging system should consider histopathologic findings.